In an image sensor with the configuration in the related art where a photodiode is provided on a silicon substrate and a color filter is formed thereon, the usage efficiency of light deteriorates since there is loss of light due to the color filter.
In addition, since the wavelength of light which is transmitted by the color filter is limited, an optical low pass filter is necessary in order to prevent the generation of false colors when reproducing colors and loss of light occurs also with the optical low pass filter.
In order to improve on such issues, a photoelectric conversion device which employs an organic photoelectric conversion material is proposed (for example, refer to JP-A-2003-332551, JP-A-2005-303266, and JP-A-2006-100767).
In a case where the photoelectric conversion device which employs an organic photoelectric conversion material is used in a color imaging apparatus (image sensor), it is possible to carry out photoelectric conversion of input light in an inner portion of the organic photoelectric conversion material without any loss due to the color filter occurring.
Due to this, it is possible to improve the use efficiency of light.
The photoelectric conversion device which employs an organic photoelectric conversion material is able to be configured by, for example, providing a photoelectric conversion film formed from an organic photoelectric conversion material between a first electrode and a second electrode and by using a conductive material which has light transparency on the electrode which is on the light irradiation side. As the conductive material which has light transparency, examples include ITO (Indium Tin Oxide) and the like, and normally, the conductive material has a large work function.
Here, in the photoelectric conversion devices which are proposed, an organic photoelectric conversion material such as a quinacridone derivative is used as the photoelectric conversion film. In a case where a quinacridone derivative is used, there is an advantage in that the efficiency of photoelectric conversion is improved.
However, since the ionization potential of quinacridone derivatives is small, hole injection leakage current is easily generated when a positive voltage is applied to an electrode with a large work function.
As a result, the current value is large even in a state where there is no light, that is, the current during darkness increases, and as a result, sensitivity is decreased.
Therefore, the application of a work function adjustment film and the like other than the photoelectric conversion film is proposed (for example, refer to JP-A-2007-81137) in order to reduce the hole injection leakage current and improve sensitivity.